It can be done (it has been done), but there is a lot of modifying required to make it work.
Yep me too, I am not sure what part are identical.
But I think
rear grab rail
I think I would get more joy from knowing what wasn't exchangeable!!
for example 500 heads on a 650?? will it fit
650 turbo on a 500?? will it fit
rear shock?? I know the euro fits cos I've done it(1" shorter)
Food for thouught